Remote control for electric transmission systems



Nov. 16, 1948. w. A. DERR 2,454,140

REMOTE CONTROL FOR ELECTRIC TRANSMISSION SYSTEMS I Filed July 20, 1946 2 Sheets-Sheet 1 bs/af/on Can fro p/iipa/qh/ ny O/filce 9 50 Q .50 7 5uperw5ar y Cofl/fo/ .583 r'irn Mover WITNESSES: Gan/F584 I INVENTOR M Hard/ZDeffi ATTOR Y Nov. 16, 1948. w. A. DERR 2, 0

REMOTE CONTROL FOR ELECTRIC TRANSMISSION SYSTEMS Filed July 20, 1946 2 Sheets-Sheet 2 WITNESSES? INVENTOR 4 I Mil q oflperr.

Patented Nov. 16, 1948 REMOTE CONTROL FOR ELECTRIC TRANSMESSION SYSTEMS Willard A. Derr, Pittsburgh, Pa, assignor to Wesim inghonse Electric Corporation, East Pittsburgh,

a corporation of Pennsylvania Application July 20, 194.6, Serial No. 685,060

10 Claims.

Another object of my invention is to provide for selectively reversing the polarity of a voltage produced by a rectifier synchronizing transmitter in accordance with whichever of two alternating current systems has the higher frequency.

It is an important object of my invention to providefor obtaining a synchronizing indication from a remote station through a supervisory con trol point for operating a circuit breaker at the remote station so that the operator may determine when to close the breaker.

It is also an object of my invention to provide for using a frequency difference transmitter to control the connection of a rectifier synchronizing transmitter to a signal system at a remote station, so as to provide a directional indication of the difference between the frequencies of two systems which are to be synchronized from a remote station.

Other objects will, in part, be obvious and will in part be explained hereinafter.

In practicing my invention a frequency diiierence transmitter which is selectively responsive in accordance with whichever of two systems to be synchronized has the higher frequency, is arranged to be connected to the systems at a remote substation upon selectionof the circuit breaker point through a supervisory control system from a dispatching office. The frequency difference transmitter selectively controls the connection to the signal channel of the supervisory control system of a rectifier synchronizing transmitter which produces a unidirectional voltage proportional in magnitude to the diffeence between the frequencies of the systems. A meter is connected to the signal channel at the control station upon the receipt of the point selection check code, which is selectively responsive to the magnitude and direction of the voltage applied to the signal channel at the remote station. An indication is thus provided both of the difierence between the frequencies of the two systems and of which system has the higher frequency, so that the operator may make the necessary changes in the frequency of one or the other of the systems for effecting synchronization.

For a more complete understanding of the nature and the scope of my invention, reference may be made to the following detailed description which may be studied in connection with the accompanying drawings in which:

Figure 1 has a diagrammatic view of the supervisory control equipment at the dispatching ofiice and remote substation in a synchronizing system embodying the invention in one of its forms; and

Fig. 2 is a diagrammatic view of the synchronizing indication transmitting means used in connection with the supervisory control equipment of Fig. 1.

The invention has been illustrated as applied to a supervisory control system which is substantially identical with that shown in Patent No. 2,091,301, which issued on August 31,1937, to H. P. Boswau, though the invention is not limited to use with such a system, but may also be used with control systems of other types. For the purpose of simplification, the supervisory control equipment of Figures 1 through 4 of the Boswau patent has been represented by the boxed. enclosures 500 and Edi, which represent the dispatching oflice and the substation supervisory control equipment, respectively. Since a principal portion of the supervisory control equipment of the Boswau patent is used with the present invention unchanged, much of the equipment has not been illustrated in detail, in order to avoid confusion. Those portions of the equipment which have been altered in any respect have been shown in windows in their respective enclosures. Relays, armatures and conductors of the Boswau patent which have been unchanged themselves, but which are closely associated with a change in the original circuit or with equipment added for the purpose or" this invention, have been shown with the same designations as in the Boswau patent hereinabove referred to, in connection with the circuit changes. Additional equipment and circuits added to the original supervisory control equipment of the Boswau patent for the purpose of the present invention have been shown positioned in front of the boxed enclosures, or to one side thereof, and are designated by numerals not appearing in the original Boswau patent.

In order to adapt the supervisory control equipment of the Boswau Patent No. 2,091,301 for continuous metering indications, the line circuit or signal channel connections comprising conductors H and 223 extending between the dispatching oifice and the substation has been changed from a series circuit to a parallel circuit, so that the line relays 200 and 400 of the Boswau patent are now connected in parallel circuit relation between the conductors 2 l0 and 223, which are arranged to be connected to the positive and negative terminals of sources of electrical energy at the dispatching office and at the substation by means of the driving relays 20! and 4M, respectively. The connections of the armatures of the line relays 200 and 400 have also been changed to conform with the normally deenergized positions of these relays.

In order to provide for producing a synchronizing indication at the dispatching office so that the operator may be able to more readily control the operation of a remote circuit breaker 503 at the substation which connects remote and local sources of alternating current 505 and 5M, means such as the rectifier synchronizing transmitter 508 may be provided at the remote substation. The synchronizing transmitter 508 may, for example, comprise a pair of potential transformers 509 and 5 l 0 which may be connected to the source 505 and 501, respectively, for applying an alternating current voltage to a rectifier bridge circuit 5|2 so as to produce a unidirectional voltage which is proportional to the difference between the frequencies of the sources. A suitable filter 5 I 4 may be connected across the output terminals of the rectifier bridge circuit 5 to remove the ripple therefrom.

For the purpose of providing an indication, not only of the magnitude of the difference between the frequencies of the two sources, but to also indicate which of the sources has the higher frequency, means such as the frequency difference transmitter 5i5 may be used to control the connection of the rectifier synchronizing transmitter 500 to the signal channel conductors M9 and 223. The frequency difference transmitter may, for example, comprise a pair of alternating current motors 5ft and 5H which may be connected to a differential device 513 to selectively actuate a movable contact arm 5 i 0 for controlling the operation of a reversing switch 520. The switch reversibly connects the rectifier synchronizing transmitter 5538 to conductors 52i and 522 which lead to the signal channel. The motors 5l6 and 5H may be energized through suitable control transformers 524 and 525 which may be connected to the source 505 and dill, respectively.

In order to provide for producing a synchronizing indication for the operator at the dispatching office, means such as the meter 52? may be provided, which is responsive to the polarity and magnitude of a voltage applied to the signal channel. The connection of the synchronizing meter 52! to the signal channel conductors 2 l0 and 223 may be controlled by means of a transfer relay 528 which selectively connects the conductors H9 and 223 through armatures 520 and 530 to either the line relay 206, or to the synchronizing meter 521. Operation of the transfer relay may be effected by means of a transfer control relay 532 which is arranged to be energized through normally closed contacts of the alarm relay I21, normally open contacts of the check code receiving relay 209, and normally open contacts of the 503 to connect the source 505 and f.

point selection relay I33. Reset control relays 534 and 535 of the time delay dropout type may be provided for effecting energization of line conductors 2 l9 and 223 to transmit a reset pulse for effecting disconnection of the rectifier synchronizing transmitter from the line conductors at the remote station when the operator actuates the master key Hill to provide for closing the circuit breaker in the usual manner.

Control of the synchronizing transmitter 500 and the frequency difference transmitter 5 l 5 may be effected by means of a control switch 540 which controls the energization of the potential transformers 509 and 5H] and the motors H6 and 55'! through normally open contact members 540a and 5401). Operation of the control switch 540 may be effected by connecting its operating winding 54] to a suitable source of electrical energy through a front contact and armature 542 of the point code relay 309 of the circuit breaker control point, The synchronizing transmitter 508 may be connected to the signal channel through a front contact and armature 543 of the point code relay 309 under the control of a transfer relay 545 which is arranged to selectively connect the line conductors 2|!) and 223 either to the line relay 400, or to the synchronizing transmitter through armatures 546 and 541.

Operation of the transfer relay 545 be effected by means of transfer control relays 54S and 549. The transfer control relay 549 may be energized upon operation of the substation start control relay M8. The transfer control relay 543 is thereupon energized. Both of these relays are of the time delay dropout type, so that an energizing circuit may be provided for the transfer relay 545 and an auxiliary control relay 550, upon deenergization of the control relay 549. Means such as the series reset relay 552 may be provided in connection with a substation shunting resistor 553 for returning the transfer relay 545 to the deenergized position upon receipt of a reset pulse from the dispatching office.

With the circuit breaker 503 in the open posi tion and the system deenergized, the operator actuates the point selection key H4 at the dispatching ofiice to select the control point in the usual manner for operating the circuit breaker Operation of the point selection key H4 results in the point selection code for the circuit breaker point being transmitted in the manner which is de scribed in detail in the Boswau patent hereinbefore referred to. Upon receipt of the point selection code the substation start control relay H8 will be energized. At the end of the point selection code, the circuit breaker point code relay 300 picks up and effects operation of the supervisory control equipment to transmit the point selection check code.

As soon as the point code relay 309 picks up, an obvious energizing circuit is provided for the operating winding 54| of the control switch 540 through front contact and armature 542. The rectifier synchronizing transmitter 508 and the frequency difference transmitter 5E5 are thereby energized from the source 505 and 501 through contact members 540a and 540?).

At the end of the point selection check code the check code receiving relay 209 at the dispatching office remains energized for a predetermined time after the point selection relay I33 is energized. Accordingly, an energizing circuit is provided for a predetermined time, for the transfer control relay 532, extending from indirect positive through armature 55B" and front con tact, conductor 551, armature 559 and back contact of the alarm relay I21, armature 569 and front contact of the relay 209, through the transfer control rela 532 to negative.

When the relay 2B9 drops out after a predetermined time delay, the energizing relay for the control relay 532 is interrupted. Since the relay 532 is of the slow dropout type, armature562 remains in contact with its front contact for .a predetermined time. This permits completing an energizing circuit for the transfer relay 523, which extends from negative through a control resistor 553, relay 528, front contact an'darmature 562 of the transfer control relay 532-, back contact and armature 55B of the check code receiving relay 209, back contact and armature 559 of the alarm relay I21, conductor 551 and front contact and armature 5 56 ofthe point selection relay.

The transfer relay 528 operates and-locks in to indirect positive through front contact and armature 565. The line conductors 219 and 223 are transferred from the line relay 209 to the synchronizing meter 521 at armatures'529 and 535, respectively. At the same time an energizingcircuit'is prepared for resetcontrol relay- 535 through front contact and armature 556 of the transfer relay. Reset control relay 535 completes an energizing circuit for the reset control relay 535 through front contact and armature 568. Op eration. of these relays disconnects the line relay 200 and the drive relay 20! from the supervisory control equipment.

At the remote station an energizing circuit is provided for the transfer control relay 549 upon transmission of the point selection check code. This circuit extends from negative through armature 510 and front contact of the drive relay 501, conductor 51! relay 549, front contact and armature 513 of the substation start control relay 418, conductor 514, and front contact and armature 542 of the point code relay309 to indirect positive. Operation of the relay 549 provides an obvious energizing circuit for the control relay 548'. Since the control relay 549 is of the delayed dropout type, it remains in the energized position throughout the transmission of the point selection check code. Upon termination of the check code, the energizing circuit for the control relay 549 is interrupted at armature 510 of the driving relay 50!. Relay 549 drops out and the energizing circuit for the control relay 548 is thus interrupted. Since the relay 548 is also of the time delay dropout type it remains in the energized position for a predetermined interval of time. An energizing circuit is thereby provided during a predetermined time for the transfer relay 545, ex'tending from negative through the relay 545, through the auxiliary transfer relay 559, conductor 519, front contact and armature 511 of the control relay 548, and back contact and armature 518 of the control relay 549. Relays 545' and 559 are thereupon sealed in to indirect positive through front contact and armature 580 of the auxiliary control relay 559.

Transfer of the synchronizing meter 521 to the signal channel at the dispatching ofiice preferably occurs slightly in advance of the connection of the rectifier synchronizing transmitter 508 to the signal channel of the remote station; so as to prevent the metering current from being put on the signal channel before the supervisory control equipment at the dispatching office is disconnected therefrom. The reset resistor 563 at the substation is arranged to bypass a greater portion of the output from the rectifier synchronizing transmitter 508 so as to permit, for example, approximately 1 mil of current maximum to flow in the signal channel for effecting a syn-- chronizating indication. This precludes any operation of the reset relay 552 in response to the synchronizing indication current.

At the dispatching office the synchronizing meter 521 indicates both the magnitude and polarity of the potential applied to the signal channelfrom the rectifier synchronizing transmitter. The magnitude of this current is proportional to the difierencc between the frequencies of the sources 505 and 591. The polarity of this potential is controlled by the reversing switch 528 which Will be in the energized or deenergized position, depending upon Whether the contact arm 519 of the frequency difference transmitter 5H5 is actuated toward the left to engage the stationary contact member 51911 or to the right to en.- gage the stationary contact member 51%. The direction of operation of the contact arm 519 is selectively responsive to the direction of the differential between the frequencies of the source 595 and 591.

Accordingly, for example, a positive voltage may be applied to the signal channel to actuate the pointer of the synchronizing meter 521 to the left of center When the frequency of the source 595 is the greater and a negative voltage may be applied to the signal channel through the switch 529 to actuate the pointer of the synchronizing meter to the right of center when the frequency of the source 591 is the greater.

The operator may then readily bring the frequencies of the two sources into agreement by changing the speed of the prime mover 582 of the generator source by means of a control device 583 which may be operatively connected to the governor 524 of the prime mover, through suitable means such as the synchrotie system 585.

As soon as the synchronizing meter 521 is centered, thus indicating a zero difference between the frequencies of the two sources, the operating key Hi) of the circuit breaker control point may be actuated to the closed position, and the master key 52 actuated to close the circuit breaker. The transfer relay 528 is thereupon shunted by an impulse which would normally be applied to the drive relay 22535 for initiating an operation, but which is applied to the transfer relay through armature 595 and front contact. The synchronizing meter 52'. is disconnected from the line conductors 2 and 223 by the return of the transfer relay 528 to the deenergized position. The line conductors are thereupon connected to positive and negative, respectively, through armature 581 and front contact of reset control relay 535, and armature 538 and front contact of reset control relay 534, respectively.

This applies a reset pulse of electrical energy to the signal channel which is of sui'licient magnitude to operate the series reset relay 552 through the path provided at the remote station through the reset resistor 553. After a predetermined interval of time, the reset control relay 535 returns to the'deenergized position since this energized circuit was interrupted at armature 555 of transfer relay. This terminates the reset pulse. Subsequent return of the reset control relay 534' to the deenergized position reconnects the signal 7 channel to the line relay 200 and reconnects the line relay and the driving relay 2M for normal operation in the supervisory control system.

At the remote station the reset relay 552 picks up in response to the reset pulse transmitted before deenergization of the transfer relay 528. A shunting circuit is provided around the auxiliary control relay 55! through front contact and armature When the reset control relay 535 at the dispatching oihce deenergizes and re moves voltage from the signal channel, the reset relay signal 552 drops, and interrupts the energizing circuit for the transfer relay 545 at armature 5. 363. The signal channel is thereby disconnected from the rectifier synchronizing transmitter see and is reconnected to the line relay iv'iil through armatures M5 and 5M and back contacts for normal operation of the supervisory control equipment.

The circuit breaker closing relay 3 i i may thereupon be operated through transmission of the operating code and operation check code in the usual manner. The synchronizing meter and rectifier synchronizing transmitter will be reconnected to the signal channel upon transmission of the operation check code. The signal channel is subsequently reconnected to the supervisory control equipment in a manner similar to that hereinbefore described upon transmission of the reset pulse.

From the above description and accompanying drawings, it will be apparent that I have provided in a simple and effective manner for indicating to an operator during the sequence of operation, the synchronizing condition between two remote sources which are to be connected by a circuit breaker operated by the supervisory control systern. Not only is the degree of difference between the frequencies of the sources indicated, but the direction of the diiierence or which source has the higher frequency, is also indicated, whereby the operator may readily bring the sources into synchronization and complete the operation by operating the operate key and master key of the supervisory control equipment in the usual manner. A system embodying my invention requires the addition only of a minimum of equipment to any supervisory control system and it provides a prompt indication which does not retard the synchronizing operation.

Since certain changes may be made in the above described construction and certain embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the above description and shown in the accompanying drawings may be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. A signal system comprising, indicating means responsive in accordance with the polarity and magnitude of an applied voltage, circuit means producing a unidirectional voltage proportional to the difference in frequency between two sources of electrical energy, and means selectively responsive to the direction of the difference in frequency between the sources operable to connect the circuit means to the indicating means in opposite senses in accordance with the direction of the frequency difference.

2. In a remote signal system having a signal channel extending from a control station to a remote station, circuit means at the remote station disposed to produce a unidirectional voltage proportional in magnitude to a difference in fre" quency between two alternating current sources, control means selectively responsive to the direction oi the difference in frequency operable to selectively connect the circuit means to the signal channel in opposite senses, means at the control station selectively responsive to the polarity and the magnitude of the voltage produced by the circuit means and relay means at the remote station controlled from the control station operable to connect the circuit means and the control means to the alternating current sources.

3. For use in a signal system having a signal channel connecting a control station to a remote station, circuit means including a unidirectional device arranged to be connected to a pair of alternating current sources for producing a unidirectional voltage proportional to a difierence in frequency between the source, control means responsive to the diiierential in frequency between the sources operable to effect selective connection of the circuit means to the signal channel depending upon which of the sources has the higher frequency, means at the control station responsive to the magnitude and polarity of the voltage applied to the signal channel, and relay means at the remote station operable from the control station to effect connection of the circuit means and. control means to the sources.

4. The combination in a supervisory control system having control and remote station supervisory control equipment operable over a signal channel of circuit means at the remote station arranged to produce a unidirectional voltage proportional to the magnitude of a difference in frequency between two alternating current systems, control means at the remote station selectively responsive to whichever of the systems has the higher frequency to reversibly effect connec tion of the circuit means to the signal channel, indicating means at the control station selectively responsive to the magnitude and polarity of the Voltage applied to the signal channel, and means selectively responsive to operation of the supervisory control equipment to eilect connection of the indicating means and the circuit means to the signal channel and of the circuit means and the control means to the alternating current systems 5. ihe combination with supervisory control system having supervisory control equipment at remote and control stations operable over a signel channel to effect selective operation over a number of different points of apparatus at the remote station including a circuit breaker operable to connect two alternating current sources, of circuit means at the remote station operable to produce a variable control voltage proportional to a difference between the frequencies of the sources, control means at the remote station operable to effect reversible connection or the circuit means to the signal channel in accordance with the direction of the difference in the frequencies or" the sources, meter means at the control station disposed to be connected to the signal channel in response to selection of the circuit breaker point, and relay means at the remote station responsive to selection of the circuit breaker point to connect the circuit means and the control means to the sources.

6. The combination with supervisory control system having supervisory control apparatus for controlling apparatus over a number of points at a remote station from a control station including point selection and check code responsive relays at the control station and code control relays and check code control relays at the remote station for operating over a signal channel, a circuit breaker connecting two alternative current sources of a rectifier synchronizing transmitter at the remote station, producing a voltage proportional to the difference in the frequencies of the sources, a frequency difference transmitter at the remote station operable to selectively effect connection of the synchronizing transmitter to the signal channel in opposite senses, means responsive to operation of the remote station check code control relay and point code relay to effect connection of the synchronizing transmitter and the frequency difference transmitter to the sources, meter means at the control station responsive to the magnitude and polarity of a voltage applied to the signal channel at the remote station and circuit means including contact members of the point selection relay and the check code responsive relays connected to effect connection of the meter means to the signal channel after the circuit breaker point is selected.

7. The combination with supervisory control equipment at control and remote stations operable over a signal channel to select a control point for a circuit breaker at the remote station disposed to connect two alternating current sources, of means at the remote station effective to produce a unidirectional voltage proportional to a difference in frequency between the sources, control means selectively responsive to'effect reversible connection of said means to the signal channel in opposite senses depending upon which source has the greater frequency, relay means responsive to selection of the circuit breaker point to effect connection of the said means to the two sources, indicating means at the control station operable in accordance with the magnitude and polarity of the voltage applied to the signal channel, and means responsive to selection of the circuit breaker point operable to connect the signal channel to the indicating means.

8. The combination in a supervisory control system having control station and remote station supervisory control equipment operable over a signal channel to select a circuit breaker control point and operate the circuit breaker to connect two alternating current sources at the remote station, of frequency responsive means at the remote station operable to produce a reversible unidirectional voltage proportional in magni tude to a difference in frequency between the sources and having a polarity which is dependent upon which source has the greater frequency, transfer means at the remote station operable in response to selection of the circuit breaker control point to disconnect the channel from the supervisory control equipment and connect it to the frequency responsive means, indicating means at the control station selectively responsive to the magnitude and polarity of an applied voltage, transfer means at the control station responsive to the selective and check of the circuit breaker control point to transfer the signal channel from the supervisory control equipment, control means at the remote station operable in response to a predetermined voltage pulse applied to the channel from the control station to render the transfer means at the remote station inoperative, and circuit means at the control station operable to render the transfer means at the control station inoperative in response to operation of the supervisory control equipment to operate the circuit breaker and to effect application of a voltage pulse to the signal channel.

9. The combination with a supervisory control system having a signal channel for controlling and supervising operation of a circuit breaker connecting two alternating current sources at a remote station, of control means at the remote station including a transfer relay responsive to selection of the circuit breaker point and relay means responsive to a difference in frequency of the sources, said control means being operable to apply to the signal channel a voltage proportional to a difference in frequency between the sources and having a polarity dependent upon which source has the greater frequency, indicating means at (the control station responsive to the selection and check of the circuit breaker point arranged to be connected to the signal channel for operation in accordance with the voltage applied thereto from the remote end.

10. For use in a system for synchronizing a pair of alternating current sources arranged to be connected at a remote station by a circuit breaker which is controlled over a point of a supervisory control system having a signal channel connecting the remote station to a control station, control means at the remote station including transfer means operable in response to selection of the circuit breaker point and reversing means operable to apply a reversible variable voltage to the signal channel sensitive to the direction and magnitude of a difference in frequency between the sources, indicating means at the control station operable in accordance with the voltage applied to the signal channel to indicate the direction and magnitude of the frequency difference between the sources, and means operable to connect the indicating means and the means at the remote station to the signal channel in response to selection of the circuit breaker point, said means being operable in response to operation of the supervisory control system to operate the circuit breaker to disconnect said means from the signal channel.

WILLARD A. DERR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,314,692 Derr Mar. 23, 1943 2,342,125 Derr Feb. 22, 1944 

